<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script src="vue.js" type="text/javascript" charset="utf-8"></script>
</head>
<body>
<div id="app">
	{{a}}
</div>

<script type="text/javascript">
var data = { a : 1 };
var vm = new Vue({
	el   : "#app",
	data : data
});

vm.$watch('a', function(newVal, oldVal){
	console.log(newVal, oldVal);
})

vm.$data.a = "test...."

</script>

</body>
</html>
